U.S. patent application number 15/185569 was filed with the patent office on 2017-01-05 for process fired heater configuration.
The applicant listed for this patent is UOP LLC. Invention is credited to Charles M. Brabson, Rajeswar Gattupalli, Matthew Martin, Quan Yuan.
Application Number | 20170003017 15/185569 |
Document ID | / |
Family ID | 57682804 |
Filed Date | 2017-01-05 |
United States Patent
Application |
20170003017 |
Kind Code |
A1 |
Yuan; Quan ; et al. |
January 5, 2017 |
PROCESS FIRED HEATER CONFIGURATION
Abstract
An apparatus for a fired heater is presented. The fired heater
is designed with process coils inside a shell, and with a
positioning of the burners for reducing the size of the fired
heater. The shell has a general rectangular prismatic shape with
combustion inlets for admitting combustion gases from the burners,
and the process coils include at least two inlet ports and at least
one outlet port.
Inventors: |
Yuan; Quan; (Buffalo Grove,
IL) ; Martin; Matthew; (Tulsa, OK) ;
Gattupalli; Rajeswar; (Buffalo Grove, IL) ; Brabson;
Charles M.; (Humble, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
UOP LLC |
Des Plaines |
IL |
US |
|
|
Family ID: |
57682804 |
Appl. No.: |
15/185569 |
Filed: |
June 17, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62186528 |
Jun 30, 2015 |
|
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|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F22B 21/02 20130101;
F22B 37/16 20130101; F22B 37/22 20130101; F22B 37/228 20130101;
F22B 37/244 20130101 |
International
Class: |
F22B 37/22 20060101
F22B037/22; F22B 37/16 20060101 F22B037/16 |
Claims
1. An apparatus for heating a process fluid, comprising: a shell
having sides, an upper surface, a lower surface, combustion fluid
inlets and a flue gas outlet, wherein the combustion inlets are for
admitting a fuel and oxidant mixture; at least one process coil
comprising at least two inlet ports and at least one outlet port
less than the number of inlet ports, and disposed within the shell;
and at least two burners disposed on the sides of the shell, and in
an opposing configuration.
2. The apparatus of claim 1 wherein the process coil inlet ports
and the outlet port are disposed on the lower surface of the
shell.
3. The apparatus of claim 1 wherein the process coil inlet ports
and the outlet port are disposed on the upper surface of the
shell.
4. The apparatus of claim 1 wherein the flue gas outlet is disposed
on the upper surface of the shell.
5. The apparatus of claim 1 wherein the flue gas outlet is disposed
on the lower surface of the shell.
6. The apparatus of claim 1 wherein the process coil has a
configuration of at least three tubes in a parallel orientation,
with two semi-circular tubular sections connecting the ends of the
tubes, such that the tubes and tubular sections form a coil having
a general configuration of a W, and the inlet tubes having one end
each connected to an inlet port and the central outlet tube having
one end connected to an outlet port.
7. The apparatus of claim 6 wherein the central outlet tube has a
diameter larger than the inlet tube diameters.
8. The apparatus of claim 6 wherein the shell has a substantially
rectangular prismatic shape, with a height, a depth and a width,
and wherein the process coils extend at least 70% of the height,
and the process coils are arranged across the width with the
central tubes arrayed along an axis that is in the middle of the
width of the shell, and wherein the smaller tubes are arrayed in a
position between 5% and 95% of the distance of the half-width of
the shell.
9. The apparatus of claim 7 wherein the two smaller tubes have
substantially the same inner diameter, and the central tube has an
inner diameter between 1 and 2 times the diameter of the smaller
tubes.
10. The apparatus of claim 1 wherein the shell has a substantially
rectangular prismatic shape, with a height, a depth and a width,
and wherein the burners are disposed on opposite sides of the width
of the shell, and wherein the burners are disposed within 10% of
the height of the from the bottom of the shell.
11. The apparatus of claim 10 wherein the apparatus further
includes at least a second pair of burners disposed on opposite
sides of the width of the shell and at a height between 30% and 80%
of the height from the bottom of the shell.
12. The apparatus of claim 1 wherein the shell has a substantially
rectangular prismatic shape, with a height, a depth and a width,
and wherein the burners are disposed on opposite sides of the depth
of the shell.
13. The apparatus of claim 1 further comprising: a first manifold
having an inlet and multiple outlets, wherein each outlet is in
fluid communication with the first inlet port of the process coil;
a second manifold having an inlet and multiple outlets, wherein
each outlet is in fluid communication with the second inlet port of
the process coil; and a third manifold having multiple inlets and
an outlet, wherein each inlet is in fluid communication with the
outlet of the process coil.
14. The apparatus of claim 1 wherein the shell has a substantially
rectangular prismatic shape, with a height, a depth and a width,
and wherein there are up to 120 coils and at least one pair of
burners for every 8 coils.
15. The apparatus of claim 1 wherein the shell has a substantially
rectangular prismatic shape, with a height, a depth and a width,
and wherein there are up to 120 coils and at least two pairs of
burners for every 16 coils.
16. The apparatus of claim 1 wherein the shell has a substantially
rectangular prismatic shape, with a height between 8 m and 25 m, a
depth 0.1 m to 0.5 m/coil, and a width between 6 m and 20 m.
17. An apparatus for heating a process fluid, comprising: a shell
having sides, an upper surface, a lower surface, combustion fluid
inlets and a flue gas outlet, and wherein the shell has a
substantially rectangular prismatic shape, with a height, a depth
and a width; a plurality of process coils comprising two inlet
ports, a first inlet port and a second inlet port, and one outlet
port, and disposed within the shell, wherein each coil is arrayed
in a plane across the width of the shell; and at least two burners
disposed on the sides of the shell, and in an opposing
configuration.
18. The apparatus of claim 17 wherein the coils have the inlet
ports and outlet port on the upper surface, and the flue gas outlet
is centered on the lower surface.
19. The apparatus of claim 17 further comprising: a first manifold
having an inlet and multiple outlets, wherein each outlet is in
fluid communication with the first inlet port of the process coil;
a second manifold having an inlet and multiple outlets, wherein
each outlet is in fluid communication with the second inlet port of
the process coil; and a third manifold having multiple inlets and
an outlet, wherein each inlet is in fluid communication with the
outlet of the process coil.
20. The apparatus of claim 17 wherein the burners are disposed on
opposite sides of the width of the shell, and wherein the burners
are disposed less than 10% of the height from the bottom of the
shell.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority from Provisional
Application No. 62/186,528 filed Jun. 30, 2015, the contents of
which are hereby incorporated by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to fired heaters for use in
chemical processes.
BACKGROUND
[0003] Fired heaters are common process units in chemical plants.
The fired heaters heat process streams to reaction temperatures,
and provide heat to process streams that have endothermic
reactions. A fired heater has a general configuration of a tube for
carrying a process fluid inside a shell wherein burners are used to
combust a fuel to heat the tubes.
[0004] With more complex processes, and with upgrades to processes
in chemical plants, new configurations are needed to reduce the
area taken up by fired heaters, and to provide for new efficiencies
in the heating of process fluids.
SUMMARY
[0005] The present invention is a new apparatus for a fired burner
to heat a process stream. A first embodiment of the invention is an
apparatus for heating a process fluid, comprising a shell having
sides, an upper surface, a lower surface, combustion fluid inlets
and a flue gas outlet, wherein the combustion inlets are for
admitting a fuel and oxidant mixture; at least one process coil
comprising at least two inlet ports and at least one outlet port
less than the number of inlet ports, and disposed within the shell;
and at least two burners disposed on the sides of the shell, and in
an opposing configuration. The burners can be in a symmetrical
opposing configuration, or in a staggered opposing configuration.
An embodiment of the invention is one, any or all of prior
embodiments in this paragraph up through the first embodiment in
this paragraph wherein the process coil inlet ports and the outlet
port are disposed on the lower surface of the shell. An embodiment
of the invention is one, any or all of prior embodiments in this
paragraph up through the first embodiment in this paragraph wherein
the process coil inlet ports and the outlet port are disposed on
the upper surface of the shell. An embodiment of the invention is
one, any or all of prior embodiments in this paragraph up through
the first embodiment in this paragraph wherein the flue gas outlet
is disposed on the upper surface of the shell. An embodiment of the
invention is one, any or all of prior embodiments in this paragraph
up through the first embodiment in this paragraph wherein the flue
gas outlet is disposed on the lower surface of the shell. An
embodiment of the invention is one, any or all of prior embodiments
in this paragraph up through the first embodiment in this paragraph
wherein the process coil has a configuration of at least three
tubes in a parallel orientation, with two semi-circular tubular
sections connecting the ends of the tubes, such that the tubes and
tubular sections form a coil having a general configuration of a W,
and the inlet tubes having one end each connected to an inlet port
and the central outlet tube having one end connected to an outlet
port. An embodiment of the invention is one, any or all of prior
embodiments in this paragraph up through the first embodiment in
this paragraph wherein the central outlet tube has a diameter
larger than the inlet tube diameters. An embodiment of the
invention is one, any or all of prior embodiments in this paragraph
up through the first embodiment in this paragraph wherein the shell
has a substantially rectangular prismatic shape, with a height, a
depth and a width, and wherein the process coils extend at least
70% of the height, and the process coils are arranged across the
width with the central tubes arrayed along an axis that is in the
middle of the width of the shell, and wherein the smaller tubes are
arrayed in a position between 5% and 95% of the distance of the
half-width of the shell. An embodiment of the invention is one, any
or all of prior embodiments in this paragraph up through the first
embodiment in this paragraph wherein the two smaller tubes have
substantially the same inner diameter, and the central tube has an
inner diameter between 1 and 2 times the diameter of the smaller
tubes. An embodiment of the invention is one, any or all of prior
embodiments in this paragraph up through the first embodiment in
this paragraph wherein the shell has a substantially rectangular
prismatic shape, with a height, a depth and a width, and wherein
the burners are disposed on opposite sides of the width of the
shell, and wherein the burners are disposed within 10% of the
height of the from the bottom of the shell. An embodiment of the
invention is one, any or all of prior embodiments in this paragraph
up through the first embodiment in this paragraph wherein the
apparatus further includes at least a second pair of burners
disposed on opposite sides of the width of the shell and at a
height between 30% and 80% of the height from the bottom of the
shell. An embodiment of the invention is one, any or all of prior
embodiments in this paragraph up through the first embodiment in
this paragraph wherein the shell has a substantially rectangular
prismatic shape, with a height, a depth and a width, and wherein
the burners are disposed on opposite sides of the width of the
shell. An embodiment of the invention is one, any or all of prior
embodiments in this paragraph up through the first embodiment in
this paragraph further comprising a first manifold having an inlet
and multiple outlets, wherein each outlet is in fluid communication
with the first inlet port of the process coil; a second manifold
having an inlet and multiple outlets, wherein each outlet is in
fluid communication with the second inlet port of the process coil;
and a third manifold having multiple inlets and an outlet, wherein
each inlet is in fluid communication with the outlet of the process
coil. An embodiment of the invention is one, any or all of prior
embodiments in this paragraph up through the first embodiment in
this paragraph wherein the shell has a substantially rectangular
prismatic shape, with a height, a depth and a width, and wherein
there are up to 120 coils and at least one pair of burners for
every 8 coils. An embodiment of the invention is one, any or all of
prior embodiments in this paragraph up through the first embodiment
in this paragraph wherein the shell has a substantially rectangular
prismatic shape, with a height, a depth and a width, and wherein
there are up to 120 coils and at least two pairs of burners for
every 16 coils. An embodiment of the invention is one, any or all
of prior embodiments in this paragraph up through the first
embodiment in this paragraph wherein the shell has a substantially
rectangular prismatic shape, with a height between 8 m and 25 m, a
depth 0.1 m to 0.5 m/coil, and a width between 6 m and 20 m.
[0006] A second embodiment of the invention is an apparatus for
heating a process fluid, comprising a shell having sides, an upper
surface, a lower surface, combustion fluid inlets and a flue gas
outlet, and wherein the shell has a substantially rectangular
prismatic shape, with a height, a depth and a width; a plurality of
process coils comprising two inlet ports, a first inlet port and a
second inlet port, and one outlet port, and disposed within the
shell, wherein each coil is arrayed in a plane across the width of
the shell; and at least two burners disposed on the sides of the
shell, and in an opposing configuration. An embodiment of the
invention is one, any or all of prior embodiments in this paragraph
up through the second embodiment in this paragraph wherein the
coils have the inlet ports and outlet port on the upper surface,
and the flue gas outlet is centered on the lower surface. An
embodiment of the invention is one, any or all of prior embodiments
in this paragraph up through the second embodiment in this
paragraph further comprising a first manifold having an inlet and
multiple outlets, wherein each outlet is in fluid communication
with the first inlet port of the process coil; a second manifold
having an inlet and multiple outlets, wherein each outlet is in
fluid communication with the second inlet port of the process coil;
and a third manifold having multiple inlets and an outlet, wherein
each inlet is in fluid communication with the outlet of the process
coil. An embodiment of the invention is one, any or all of prior
embodiments in this paragraph up through the second embodiment in
this paragraph wherein the burners are disposed on opposite sides
of the width of the shell, and wherein the burners are disposed
less than 10% of the height of the from the bottom of the
shell.
[0007] Other objects, advantages and applications of the present
invention will become apparent to those skilled in the art from the
following detailed description and drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a cross-sectional view of the apparatus;
[0009] FIG. 2 is a drawing of the coils and manifolds for admitting
and withdrawing the process stream to be heated in the apparatus;
and
[0010] FIG. 3 is a schematic of one array of round flame end wall
burners, from one side of the fired heater shell.
DETAILED DESCRIPTION
[0011] Chemical processes frequently need heating. Process heaters
are designed to heat feed streams or intermediate process streams
to temperatures necessary for the chemical reactions in the
processes to occur at a reasonable rate. Most fired process heaters
are equipped with "U-shaped" coils that allow for a process fluid
to be heated. The coils are mounted in fired heaters that include
burners. A fired heater is typically a box-shaped furnace with the
coils inside the box and burners mounted on the sides or bottoms of
the furnace. For a commercial process, a fired heater can be a very
large item.
[0012] In a commercial hydrocarbon processing unit, fired heaters
can represent a major portion of the capital cost. Redesigned
heaters can reduce the losses and proved for more desirable capital
cost, operation costs and reduced area, or smaller plot space,
required for a heater.
[0013] The present invention provides a new heater configuration
that includes a change in the coil geometry and burner positioning.
The present invention is an apparatus for a fired heater to heat a
process fluid. The apparatus includes a shell having a generalized
rectangular prismatic shape with an upper surface, a lower surface,
and sides. The shell includes inlets for admitting a combustion
fluid, and a flue gas outlet. The flue gas outlet can be disposed
on the upper surface or the lower surface of the shell. The flue
gas outlet can also be positioned in one or more of the sides and
within 10% of the height of the top of the sides. The apparatus
further includes at least one process coil wherein the process coil
includes at least two inlet ports and at least one outlet port. The
inlet ports and the outlet port are in fluid communication with
openings, or ports disposed in the shell surfaces. The apparatus
further includes at least two burners disposed on the sides of the
shell having burner outlets in fluid communication with the shell
inlets for admitting the combustion fluid. The at least two burners
are arranged in an opposing configuration, or on opposite sides of
the shell. In an alternate arrangement, the burners can be disposed
on the lower surface, and on opposite sides of the shell in either
a symmetrical orientation or a staggered orientation.
[0014] In one embodiment, the process coil inlet ports and the
outlet port are disposed on the upper surface of the shell. The
process coil has a configuration of at least three tubes in a
parallel orientation, with two rounded, or semi-circular, tubular
sections connecting the ends of the tubes, such that the tubular
sections combined with the tubes for a coil having a general
configuration of the letter W, with the inlet tubes having one end
each connected to an inlet port and the central outlet tube having
one end connected to an outlet port. The central outlet tube can
have a diameter larger than the inlet tube diameters, and the
central outlet tube can have an inside diameter between 1 and 2
times the diameter of the smaller inlet tubes. The diameter of the
inlet tubes is typically in the range of 2'' NPS (nominal pipe
size) to 7'' NPS.
[0015] A cross-section of the apparatus can be seen in FIG. 1,
showing one of the process coils 22. The shell of the apparatus has
a substantially rectangular prismatic shape, having a height 10, a
width 20, and a depth (not shown in the figure). The process coils
22 extend at least 70% of the height 10, and the process coils are
arranged across the width 20 of the shell. The central tubes 24 of
the process coils are arrayed near an axis along the middle of the
width 20 of the shell. The inlet tubes 26 are arrayed between the
center of the shell and the shell wall 30. The inlet tubes 26 are
positioned between 5% and 95% of the distance of the half-width of
the shell from the shell wall 30.
[0016] The apparatus includes burners 40, and the burners 40 are
disposed on the sides of the shell. The burners 40 are disposed on
opposite sides of the shell with a pair of burners 40 disposed
within 10% of the height 10 of the shell from the bottom 44 of the
shell. The apparatus can include a second pair of burners 42
disposed on opposite sides of the shell. The second pair of burners
42 are located at an elevated position relative to the first pair
of burners 40, and are disposed at a position between 30% and 80%
of the height 10 from the bottom 44 of the shell.
[0017] The apparatus can include a plurality of coils, with upwards
of 120 coils. As shown in FIG. 2, the coils have inlets and
outlets. The apparatus further includes a first manifold 110 have
an inlet 112 and a plurality of outlets, wherein each outlet is in
fluid communication with the first inlet port of a process coil 22.
The apparatus further includes a second manifold 120 having an
inlet 122 and a plurality of outlets, wherein each outlet is in
fluid communication with the second inlet port of a process coil
22. The apparatus further includes a third manifold 130 having
multiple inlets and an outlet 132, wherein each inlet is in fluid
communication with the outlet of a process coil. 22.
[0018] The fired heater provides a high temperature combustion from
burners placed at interval along the sides of the shell. The
apparatus includes at least one pair of burners for every 8 process
coils, with up to 120 process coils and the process coils are
arranged along the depth of the box with a certain minimum spacing
between the coils. The burners are in pairs on opposing sides of
the shell, and can be arrayed to have two opposing pairs of burners
with a second pair in an elevated position relative to the first
pair of burners. The apparatus can include at least two of the
pairs of burners for every 16 coils. While one arrangement has the
second pair of burners disposed directly over the first pair of
burners and spaced at a distance between 10% and 70% of the height
of the shell, another arrangement has the second pair of burners
offset along the depth of the shell relative to the first pair of
burners.
[0019] The shell has a substantially rectangular prismatic shape,
or is a box like structure, with a height 10 between 8 m and 25 m,
a width 20 between 6 m and 20 m, and a depth between 0.1 m and 0.5
m per coil in the apparatus. For a shell with 120 coils disposed
within the shell the depth will be between 12 m and 60 m.
[0020] The preferred geometry of the apparatus is for coils having
two inlet legs and one outlet leg. The coils are arrayed across the
width of the shell and the burners in the apparatus are positioned
in the side walls on the opposite sides of the width of the shell.
The burners provide a heated combustion gas that circulates in the
shell and exits a flue gas outlet. The hot circulating gas heats
the coils and the fluid inside the coils. The burner position is
related to the coil geometry, and the burners are positioned
against the radiant section of the sides, and radiate and convect
heat to the coils. It is preferred to use flat-flame burners for
the lower pairs of burners near the lower surface of the shell, and
either flat-flame burners or radial flame burners at the position
above the first pair of burners. In traditional U-tube designs with
end wall burners, the average circumferential heat flux is similar
that the inlet and outlet legs. In the present invention with the
floor fired burner arrangement, the average circumferential heat
flux at the inlet legs is much higher than the average heat flux at
the outlet legs, which helps in reducing the surface area of the
coils when compared to traditional designs.
[0021] In another embodiment, the burners are positioned in the
side walls of the opposite sides of the depth of the shell. These
burners are typically round flame end wall fired burners. FIG. 3
gives an indication of the arrangement of the end-wall burners on
one end-wall. In FIG. 3, a cross-section showing the sides 30, and
a process coil 22. The burners 50 are on the end walls of the depth
of the shell. The burners 50 can project from the end wall and
provide heating between the legs of the coils 22. Burners are
disposed on opposite end walls of the shell of the fired
heater.
[0022] In one embodiment, the flow pattern is generated to have the
hot combustion gases flow up along the inlet legs of the coils and
down along the outlet leg of the coil in a large order circulation
with smaller circulation flows around the coils, and out the flue
gas outlet in the bottom of the shell. In another embodiment, the
combustion gas circulates around the coils and exits a flue gas
outlet disposed near the top of the shell sides. The preferred flue
gas outlet is at the bottom of the shell, which improves the
efficiency of the radiant box when compared to the flue gas outlet
at the top of the shell.
[0023] The invention provides for a smaller heater, in volume,
while still delivering a desired heating capacity, as the heater
design is no longer limited by coils that have the highest absorbed
duty. This provides for a more uniform delivery of heat to all the
coils in the apparatus. A comparison was made with a standard
commercial fired heater.
TABLE-US-00001 TABLE 1 Comparison of a new charge heater designed
using this invention against a baseline charge heater for a 750
kmta propane dehydrogenation unit. Present Baseline Invention Gas
Inlet Temperature (.degree. C.) 558 558 Process Gas Outlet
Temperature 630 630 Radiant Section Efficiency 60.70% 60.90% Coils
Surface Area Relative to Baseline 100% ~72% Radiant Box Surface
Area Relative to Baseline 100% ~48%
TABLE-US-00002 TABLE 2 Comparison of efficiency in the new heater
for top and bottom flue gas duct with floor fired burners. Top flue
gas Bottom flue Duct gas duct Gas Inlet Temperature (.degree. C.)
558 558 Process Gas Outlet Temperature 630 630 Radiant section
efficiency 60.9% 48.9%
[0024] While the invention has been described with what are
presently considered the preferred embodiments, it is to be
understood that the invention is not limited to the disclosed
embodiments, but it is intended to cover various modifications and
equivalent arrangements included within the scope of the appended
claims.
* * * * *